首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   6396篇
  免费   485篇
  国内免费   71篇
耳鼻咽喉   55篇
儿科学   143篇
妇产科学   94篇
基础医学   648篇
口腔科学   131篇
临床医学   773篇
内科学   642篇
皮肤病学   61篇
神经病学   978篇
特种医学   221篇
外科学   714篇
综合类   502篇
一般理论   4篇
预防医学   976篇
眼科学   53篇
药学   671篇
  2篇
中国医学   85篇
肿瘤学   199篇
  2024年   10篇
  2023年   140篇
  2022年   207篇
  2021年   283篇
  2020年   276篇
  2019年   232篇
  2018年   273篇
  2017年   241篇
  2016年   254篇
  2015年   240篇
  2014年   393篇
  2013年   504篇
  2012年   286篇
  2011年   359篇
  2010年   297篇
  2009年   306篇
  2008年   343篇
  2007年   269篇
  2006年   247篇
  2005年   211篇
  2004年   201篇
  2003年   206篇
  2002年   135篇
  2001年   111篇
  2000年   88篇
  1999年   71篇
  1998年   79篇
  1997年   65篇
  1996年   76篇
  1995年   60篇
  1994年   57篇
  1993年   49篇
  1992年   46篇
  1991年   46篇
  1990年   33篇
  1989年   30篇
  1988年   21篇
  1987年   23篇
  1986年   25篇
  1985年   27篇
  1984年   23篇
  1983年   9篇
  1982年   14篇
  1981年   9篇
  1980年   14篇
  1979年   8篇
  1978年   10篇
  1977年   8篇
  1976年   7篇
  1972年   6篇
排序方式: 共有6952条查询结果,搜索用时 15 毫秒
21.
Summary The delayed onset of symptomatic pain following lumbar discography (with no immediate pain response) is described in six patients, five with a minimum 2-year follow-up. It is usually seen in patients with nearly normal disc morphology who have incomplete or discrete annular tears that are not filled at the time of injection. Later (2–12 h in this study), dye leakage occurs through these lesions, thereby precipitating the discogenic pain This phenomenon may be missed and is probably more common than previously believed due to early discharge from the hospital, the patient expecting discomfort after the invasive study (hence no complaint is made), and the clinician being unaware of this delayed symptom, thereby not asking about it in follow-up. Close patient questioning regarding a delayed onset of symptomatic pain after discography is, therefore, an essential element in diagnostic information following this study.  相似文献   
22.
Background  Research has demonstrated that optimism and “positive illusions” can be used a coping mechanism among those facing adversity. Gamblers are a little studied group who also experience adversity and uncertainty. They often feel considerable levels of frustration, guilt, anger and a sense of feeling cheated after making significant losses. In order to deal with such feelings it is hypothesized that these individuals will search for positive consequences from their behaviour in order to offset this negative affect. Objectives  To (1) determine whether after gambling, gamblers compensate and reduce negative affect by identifying positive consequences from experiencing a loss, and (2) identify types of strategies which gamblers employ and consider how these should be classified. Materials and Methods  Eighty-seven regular slot machine gamblers were interviewed in a variety of environments housing slot machines. Each participant was asked a series of questions in a semi-structured format, to explore possible styles of positive thinking. Results  Nine types of ‘positive thinking’ experienced by gamblers were identified. These included Comparative thinking, Prophylactic thinking, Biased frequency thinking, Responsibility avoidance, Chasing Validation, Prioritization, Resourcefulness, Thoughtfulness, and Fear Reduction. Gamblers who were positive thinkers experienced significantly less guilt than non-positive thinkers. Conclusions  While reduction of negative affect may be perceived as positive in many other contexts, it is argued that it may counteract efforts to promote responsible gambling. Clinical implications and directions for future research are discussed.  相似文献   
23.
目的探讨电离辐射诱发的基因组不稳定性效应。方法采用^60Co γ射线照射人正常肝细胞,检测克隆形成率和微核发生率,利用单细胞凝胶电泳(SCGE)技术检测DNA损伤情况。照射2、4、6、8和10Gy后传代培养,在40代后各剂量组再次统一照射2Gy,进行辐射损伤的检测。结果首次照射后,克隆形成率随受照剂量的增大而降低。存活细胞经二次照射后,SCGE结果和微核发生率结果表明,首次照射剂量与子代二次照射后的损伤程度存在剂量效应关系。结论γ射线不仅在肝细胞中产生直接的生物效应,而且还可以诱发产生可遗传的基因组不稳定性,使子代细胞中的突变频率增加,表现出滞后的遗传改变。二次事件的放大作用是研究基因组不稳定性的一种较好方法。  相似文献   
24.
25.
Subjective bias in reports of poor work adjustment in depressed patients   总被引:2,自引:0,他引:2  
Twenty-five depressed inpatients were asked to report their adjustment at work during the 4-month period preceding their hospitalization. Two separate reports were given: the first during the acute illness phase and the second one 10-28 days later, after symptomatic remission following standardized pharmacotherapy. Thirty-two percent more patient ratings showed absence of adjustment problems on the second report compared with the first. Significant differences between the 2 reports were found in 7 of the 9 items on the Structured and Scaled Interview to Assess Maladjustment, which is designed to assess specific aspects of maladjustment at work. The changes in the scores of maladjustment correlated with the changes in the scores of depressive symptoms, and 40% of the variation in maladjustment scores was accounted for by the pessimism item of the Montgomery-Asberg Depression Rating Scale. Much of the poor work adjustment reported by the acutely depressed patients thus seems to be caused by symptom-related subjective bias.  相似文献   
26.
Changes in MAP2 and clathrin immunoreactivity were studied in gerbil hippocampus after transient cerebral ischemia. MAP2 immuno-reactivity decreased significantly by 1 h in the subiculum-CA1 and CA2 areas which correspond to reactive change, while no decrease was observed in CA1 until day 4. Before the initiation of delayed neuronal death, MAP2 immunoreactivity was not changed in CA1. On the other hand clathrin immunoreactivity increased in the pyramidal cell layer of CA1 by 3 h after ischemia and remained high for 2 days. Clathrin immunoreactivity in the pyramidal cell layer of CA1 diminished after delayed neuronal death. The transient change of clathrin was noted especially in CA1 in the period prior to delayed neuronal death. These results imply an abnormal change in clathrin turnover after ischemia, which may participate in the pathogenesis of delayed neuronal death.  相似文献   
27.
对TOCP染毒母鸡进行为期7周的神经电生理监测,结果表明,TOCP主要影响远端周围神经,导致坐骨神经远端MCV和SCV减慢及腓肠肌EMG失神经样改变,而胫后神经H反射及重复电刺激无明显异常。  相似文献   
28.
本实验通过结扎沙土鼠双侧颈总动脉20分钟,再灌流7天内,动态观察背侧海马组织的形态学变化。光镜观察表明:海马各区对缺血的反应性不同,其中以 CA_1区锥体细胞对缺血最为敏感,并且 CA_1区神经元的损伤是迟发性的,再灌流4天后才出现大量神经元的坏死、消失,即“迟发性神经元死亡”(NDN)。电镜下发现:缺血再灌流早期(1~2天),CA_1区神经细胞质内有大量粗面内质网增多。本实验结果表明:短暂性脑缺血所致的海马损伤与脑组织其他区域神经元损伤不同。  相似文献   
29.
The effects of several opioid agonists and antagonists were examined in pigeons performing under a delayed matching-to-sample procedure. The mu agonists morphine and l-methadone, the kappa agonists U 50,488 and ethylketocyclazocine, and the opioid antagonist naloxone had no effect on the accuracy of responding. These drugs were, however, behaviorally active as evidenced by the dose-dependent decreases in rates of responding associated with their administration. In contrast, the sigma agonists (+) N-allylnormetazocine and phencyclidine decreased the accuracy of responding in a dose-dependent fashion. The relative magnitude of these drug-induced decreases in accuracy were similar across the no delay (0-s), short (2-s), and long (8-s) delay intervals. For these drugs, accuracy-decreasing effects were obtained only at doses that reduced rates of responding. The results of the present investigation parallel those reported in pigeons responding under drug discrimination tasks, in which the discriminative stimulus properties produced by the mu and kappa agonists are similar to each other but distinguishable from those produced by the sigma agonists.Recipient of Research Scientist Development Award DA 00033 from the National Institute on Drug Abuse  相似文献   
30.
重症肌无力术后延长拔管时间的临床价值   总被引:6,自引:0,他引:6  
目的 探讨重症肌无力 (MG)胸腺切除术后 ,延长气管拔管时间 ,减少气管切开的价值。方法 回顾分析 1978年至 2 0 0 2年 12月行MG胸腺切除 2 36例 ,按时间分A组 :1996年 12月以前手术者116例 ,对术后可能发生肌无力危象的高危因素病人施行预防性气管切开 ;B组 :1997年后手术 12 0例 ,对具发生危象高危因素者采用延长气管拔管时间 ,并对两组危象发生率及气管切开率进行比较。结果 全组发生危象 4 4例 (18 6 % ) ,气管切开 4 6例 (ARDS 1例除外 )占 19 5 %。其中A组发生危象 2 3例(19 8% ) ,气管切开 34例 (2 9 3% ) ;B组发生危象 2 1例 (17 5 % ) ,气管切开 12例 (10 % )。两组危象发生率无明显差异 ,但A组的气管切开率明显高于B组 (P <0 0 0 1)。结论 对MG胸腺切除术后具发生危象高危因素病人 ,采用延长气管插管时间及辅助通气 ,可显著减少气管切开率。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号